Respirology | APSR Respiratory Medicine Journal
What Are Lung Carcinoid Tumors?
If you or someone you know has been diagnosed with carcinoid tumors in the lung, you may wonder what they are and how they're different from other types of lung cancer.
Carcinoid tumors are a rare type of lung cancer. Only 1% to 2% of lung cancers are carcinoid tumors. They usually grow slowly. They are a type of neuroendocrine tumor, meaning that they start in special cells, called neuroendocrine cells, that are found in the lungs and throughout the body.
It's important for you to know what kind of carcinoid tumor you have to get the best treatment. Carcinoid tumors are divided in two types: typical and atypical.
Typical carcinoid tumors are the most common. About 9 out of 10 carcinoid tumors are called typical. They grow slowly, and they don't usually spread outside of the lungs.
Atypical carcinoid tumors grow faster, and they're more likely to spread, or metastasize, outside of the lungs.
Doctors also refer to lung carcinoid tumors based on their location. If your tumors are in the walls of the large airways of your lungs, they're central carcinoids. If they're found in the smaller airways closer to the edges of your lungs, they're peripheral carcinoids.
The outlook is often good. Among people with typical carcinoid tumors of the lung, about 85% to 90% live another 5 years or more, as do 50% to 70% of those with atypical carcinoids.
Researchers don't really know the causes of carcinoid tumors in the lung. They have found that typical carcinoids don't seem to be linked to smoking, but atypical carcinoid tumors are found more often in people who do smoke.
You may be at a higher risk for these rare tumors with:
Age. You can get carcinoid tumors at any age, but they happen most often in people 45 to 55 years old.
Gender. Carcinoid tumors are more common in women than in men.
Race/ethnicity. These tumors are more common in whites than in other racial and ethnic groups.
Family history. Your risk is higher if you have family members with carcinoid tumors.
Multiple endocrine neoplasia type 1. This inherited syndrome raises your chances of getting lung carcinoid tumors, as well as tumors in the pancreas and the pituitary and parathyroid glands.
You may not have any symptoms. Around 25% of people with these tumors don't. Your doctor may discover them when you have tests for something else.
Carcinoid tumors in the lung may cause:
Sometimes carcinoid tumors cause a condition called carcinoid syndrome. That's due to the hormones released by the cells in the tumors. Symptoms may include flushing of your face and neck, diarrhea, fast heart rate, and weight gain.
Your doctor will ask you questions about your medical history (that includes your family history) and examine you, listening to your lungs.
These tests can help diagnose carcinoid tumors:
Chest X-rays may show whether any tumors are in your lungs. Some may be too small or in locations that can't be seen with standard X-rays.
CT scans use X-rays and a computer to give a cross-section view of your lungs and can also show if any tumors have spread to other organs, such as your liver.
Blood and urine tests may find substances that carcinoid tumors sometimes release. Serotonin or chromogranin-A in the blood may be a sign of a typical carcinoid tumor. The level of 5-HIAA, a byproduct of serotonin, can show up in your pee.
A biopsy is a sample of tissue taken from your tumor and checked under a microscope. It can be done two ways. If you have a nonsurgical biopsy, you'll probably be sedated. Your doctor may insert a bronchoscope, a type of thin, flexible camera, into your lungs to look at the tissue. If you have a surgical biopsy, you'll have anesthesia and may need to stay in the hospital. It will take longer to recover, too. Your doctor will have to make small surgical cuts in your chest to get the sample of tissue.
The stage of your cancer is based on the size of your tumor and whether it has spread to nearby lymph nodes or other parts of your body. Knowing the stage helps you and your doctor weigh your treatment options.
Stages range from 0, the earliest, to IV, the most advanced. Doctors sometimes use letters along with the stage number to break it down even more.
Your doctor can help you understand the pros and cons of all your treatment options and what's likely to be best for you.
Surgery is usually the first choice, depending on how healthy you are, where your tumors are in your lungs, whether they're typical or atypical, and what stage they are.
You may get chemotherapy or radiation therapy, sometimes after surgery. If your tumors can't be removed with surgery or have spread or returned, your doctor may recommend targeted therapy, a special type of chemotherapy. The FDA approved everolimus (Afinitor) for this purpose in 2016. Certain drugs can ease symptoms caused by hormones that your tumors release and may slow their growth.
A clinical trial may be an option if other treatments aren't a good fit for you. In clinical trials, researchers study the safety and effectiveness of new treatments. Your doctor can help you look for a clinical trial that you may be eligible for. Make sure you know what's involved, including the risks, benefits, and where you'll go for treatment before you sign up.
Carcinoid Tumor And Bowel Obstruction
November 01, 2010
6 min read
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A 65-year-old woman with a history of type 2 diabetes, coronary artery disease with congestive heart failure and nephropathy presented with severe, intermittent, crampy abdominal pain and chronic constipation alternating with diarrhea. She complained of a long history of subjective flushing, but denied wheezing and palpitations. She was felt to have a possible bowel obstruction, and an abdominal CT scan was performed that showed a mass near the terminal ileum.
The patient’s subjective flushing symptoms with an ileal mass suggested a carcinoid tumor. A 24-hour urine 5-hydroxyindoleacetic acid (5-HIAA) test was mildly elevated at 18.4 mg per day (normal range 2 mg to 8 mg per day). Somatostatin receptor scintigraphy (SRS) with indium-111 octreotide was performed. Standard anterior and posterior imaging was unrevealing due to normal isotope trapping in the overlying normal bowel, liver and kidneys (Figure 1). However, single-photon emission CT revealed an area of increased, persistent radiotracer activity within the right side of the abdomen (Figure 2) that localized to the area of the terminal ileum. There were no other areas of isotope accumulation suggesting metastases. These findings are consistent with a midgut carcinoid tumor of the small intestine.
Carcinoid tumors are amine precursor uptake and decarboxylation-omas that arise from the enterochromaffin cells of the gastrointestinal tract. They are neuroendocrine tumors that secrete several hormones and amines. In midgut tumors, 5-hydroxytryptophan is converted by an enzyme dopa decarboxylase into serotonin (5-hydroxytryptamine). Monoamine oxidase in the blood rapidly converts serotonin to 5-HIAA, which can be measured by laboratory testing. Other potentially bioactive molecules, including histamine, prostaglandins, kallikrein and other polypeptides, can also be secreted.
Carcinoid tumors are well-circumscribed, round and submucosal masses that can be classified according to embryologic origin into foregut (bronchial, stomach, duodenum, biliary tract and pancreas), midgut (small intestine, appendix and proximal colon) and hindgut (distal colon, rectum and genitourinary tract).
The estimated prevalence is about five per 100,000, but the true prevalence is probably higher as many indolent tumors are found incidentally, such as this case.
Gastrointestinal carcinoid tumors are the most common (64%), followed by lung and bronchial tumors (28%). Of the gastrointestinal tumors, the ileum is the most common site (45%), followed by the rectum (20%), appendix (16%), colon (11%) and stomach (7%). WHO divides carcinoid tumors into four grades: well differentiated; moderately differentiated; poorly differentiated; and undifferentiated. Typical tumors with characteristic growth patterns are classified as well-differentiated neuroendocrine tumors and are slow-growing. Metastatic tumors are divided into well-differentiated and poorly differentiated tumors.
Photos courtesy of: Stephanie L. Lee, MD, PhD
Figure 2. Single-photon emission CT images of the indium-111 octreotide scan. Two adjacent tomographic images are shown. The yellow area in the left side of the panel indicates the uptake of tracer into the midgut carcinoid tumor located in the terminal ileum. The right side of the panel shows isotope uptake into the carcinoid tumor at the intersection of the crosshairs in the three orthogonal planes: coronal, sagittal and axial.
Most gastrointestinal carcinoids are sporadic and have a loss of heterozygosity of chromosome 18. Midgut â€" not foregut or hindgut â€" carcinoid tumors contain the enzyme dopa decarboxylase, which converts 5-hydroxytryptophan into serotonin. Carcinoid tumors of the foregut and hindgut are usually biologically inactive. Clinical features vary with the location of the tumor, the products secreted and the presence of liver metastases. For example, gastric carcinoids can be associated with chronic atrophic gastritis (type 1), with Zollinger-Ellison syndrome or with multiple endocrine neoplasia 1 (type 2); they may also be sporadic (type 3).
Hindgut tumors rarely secrete serotonin and usually present with bleeding or obstruction. Midgut or small intestinal tumors can secrete serotonin, but the most common clinical presentation is a prolonged, nonspecific abdominal discomfort. Serotonin is a mediator of fibrosis with intense desmoplastic and fibrotic reactions in the mesentery seen in the area of these tumors, which may result in abdominal pain or obstruction.
These tumors are frequently multiple, malignant and diagnosed late with partial, small intestinal obstruction with intermittent cramps. When the tumor is limited to a gastrointestinal location, biochemically, they are silent. The venous drainage of the gut goes through the liver before returning to the systemic circulation. The liver inactivates gastrointestinal carcinoid secretory products, so the presence of the systemic carcinoid syndrome depends on having both a secretory tumor and either liver metastases or an extraintestinal location that allows bypass of the portal circulation.
The typical carcinoid syndrome occurs in 10% of patients and is most often associated with midgut tumors. It is characterized by episodic flushing of the face, neck and upper chest, as well as the presence of watery diarrhea. As the disease progresses, the episodes of flushing may last more than 30 minutes. The prolonged vasodilation results in venous telangiectasia of the nose, upper lip and malar regions. Bronchospasm, wheezing, tachycardia and hypotension are less common. Up to 50% of patients with carcinoid syndrome develop carcinoid heart disease. The fibrous plaque-like lesions most commonly develop on the tricuspid valve and cause tricuspid regurgitation. Baseline and repeated echocardiograms are useful in monitoring for the development of disease. Advanced disease can cause pulmonary fibrosis and pleural thickening. Release of peptides such as adrenocorticotropin-releasing hormone or growth hormone-releasing factor may rarely cause Cushing’s syndrome, acromegaly or other clinical syndromes.
Carcinoid crisis is a potentially fatal complication that can develop in patients during anesthesia induction after manipulation of a tumor mass or after chemotherapy or hepatic artery embolization. Symptoms include flushing, bronchoconstriction, hypotension or hypertension, and mental status changes that last for several hours or days. Prophylaxis with octreotide is required before such procedures.
Biochemical diagnosis of carcinoid syndrome is made with measurement of the 24-hour urinary 5-HIAA, which has a sensitivity of 75% and a specificity of 100%. Malabsorption syndromes, such as celiac disease, small bowel obstruction, ingestion of tryptophan-rich foods and several medications (See chart) can alter the levels of 5-HIAA and should be avoided if possible before urine collection. Even with this interference, generally, a secretory tumor is associated with very high levels of 5-HIAA, between 99 mg and 2,070 mg per day. Chromogranin A, proteins stored in neuroendocrine cells and whole blood serotonin, are sensitive but nonspecific markers. In patients with flushing due to carcinoid syndrome, the epinephrine provocation test will result in transient flushing, hypotension and tachycardia. Other secretory products can be measured if clinically indicated, such as gastrin and histamine.
SRS with indium-111-labeled somatostatin analogue octreotide can be used to localize primary and metastatic tumors with a sensitivity of 73% to 90%. CT or MRI scans can be used to assess the size and location of the primary or metastatic tumors, calcifications and mesenteric fibrosis with a sensitivity of more than 80%. False positives on SRS can occur with granulomas, thyroid diseases and activated lymphocytes. Bronchial carcinoids are diagnosed by chest X-ray and CT scans. Endoscopy may detect tumors that were not identified on imaging studies.
Localized disease can often be cured with surgical resection. Surgery is an option for bronchial or ovarian tumors, for small bowel neoplasms to prevent the desmoplastic reaction and in select cases for hepatic metastasis resection.
Medical treatment is generally effective for symptomatic treatment in patients with extraintestinal or metastatic disease. Treatment can be symptom-specific. For example, ondansetron is a serotonin antagonist and can be used for refractory diarrhea, and histamine-secreting gastric carcinoids may respond to a histamine blocker. If symptoms are more severe, somatostatin analogues can be used.
Octreotide and lanreotide are well tolerated, available in sustained-release form and can be titrated to symptom control. These medications do not reduce the carcinoid size or slow the growth of the tumor. Interferon-alpha may be used alone or in combination with octreotide, but its use is limited by side effects. Chemotherapy and radiation have been used in patients unresponsive to medical therapies without much success. Selective ligation, embolization or chemoembolization of the branches of the hepatic artery is an alternative treatment to metastatic hepatic lesions.
Prognosis is based on tumor size, location, histology and the presence of carcinoid syndrome or metastatic disease. Median survival for patients with metastases is 5 to 8 years, although those with severe carcinoid heart disease have a 30% 5-year survival.
The patient presented underwent resection of the terminal ileum mass, which was confirmed by pathology as a carcinoid tumor without liver lesions or a documented carcinoid syndrome. Postoperatively, her 5-HIAA was lower within the reference range at 11.2 mg per day. Her intermittent mild flushing, constipation and diarrhea were unchanged postoperatively, suggesting that the carcinoid tumor was not the cause of her gastrointestinal symptoms or subjective flushing.
Varsha Vimalananda, MD, is a fellow in endocrinology; and Stephanie L. Lee, MD, PhD, is professor of medicine and associate chief, both in the section of endocrinology, diabetes and nutrition at Boston Medical Center.
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Neuroendocrine Tumors Of The Lung
Lung cancer is cancer where the tumors start in the lungs. It can either be small-cell lung cancer (SCLC) or non-small cell lung cancer (NSCLC). Most cases of lung cancer are NSCLC.
Specifically, most lung cancers start in the cells of the lungs' bronchi, or major airways. However, tumors can also develop in the neuroendocrine cells of the lungs. These types of lung tumors are unique, so symptoms, treatment, and outlook are different from other types of lung cancer.
There are several types of lung neuroendocrine tumors. SCLC is most common, but some types of NSCLC are also neuroendocrine tumors. It's important to determine your subtype, as that can influence your treatment and outlook.
Neuroendocrine tumors are tumors that begin in cells of the neuroendocrine system. These cells are found in all organs and help control many bodily functions. They receive messages from neurons (nerve cells) and release hormones.
Because neuroendocrine cells exist throughout the body, neuroendocrine tumors can form anywhere. They most commonly form in the gastrointestinal tract.
There are several types of neuroendocrine tumors, including carcinoid tumors. This is a subset of neuroendocrine tumors that are low or intermediate grade.
Because they start in hormone-producing cells, some lung neuroendocrine tumors can make hormone-like substances called neuropeptides and amines. This can lead to a potentially serious condition called carcinoid syndrome.
There are four types of lung neuroendocrine tumors, which are generally classified by:
The four types of lung neuroendocrine tumors are:
Small-cell lung cancer
Not all cases of SCLC have neuroendocrine markers. About 5% to 10% of SCLC tumors are neuroendocrine-negative. But these tumors still behave similarly to neuroendocrine-positive tumors.
SCLC is aggressive, grows quickly, and doesn't have well-defined borders. By the time doctors diagnose it, SCLC has usually spread beyond the lungs. It usually responds well to initial treatment but often returns later.
Large cell neuroendocrine lung carcinoma
Large cell neuroendocrine lung carcinoma is a subset of large cell carcinoma that's similar in many ways to SCLC. It grows and spreads quickly and is difficult to treat. It's relatively rare, making up about 3% of all lung cancers.
Large cell neuroendocrine lung carcinomas have large, quickly-dividing cells. There's often necrosis in the tumors, and they can appear in any part of the lung.
Smoking is also a major risk factor for this type of cancer.
Typical carcinoid
Typical carcinoids make up around 1% of lung cancers. Most develop in the major bronchi, which carry air into the lungs.
This type of tumor grows slowly, has well-defined borders, and rarely metastasizes. It usually doesn't have a lot of cells actively dividing and doesn't cause necrosis. It's not linked to smoking or any environmental hazards.
Atypical lung carcinoid
This type of lung cancer is very rare, making up about 0.1% of all lung cancers. It's more common in smokers, but smoking isn't as significant a risk factor as it is for other types of lung cancer.
Most atypical carcinoids develop in the major bronchi. They grow more quickly than typical carcinoids but still slower than other types of cancer. These tumors have well-defined borders, have a moderate number of dividing cells, and may or may not feature necrosis.
Diagnosis of neuroendocrine tumors of the lung involves several steps. Your doctor will first diagnose lung cancer and then determine the specific type.
Your doctor will first review your medical history. They'll ask about your symptoms, when they started, your risk factors for lung cancer, and your family history. They'll also do a full physical exam.
If your doctor suspects lung cancer, they'll do a chest X-ray, which is often enough to see a tumor. But if the chest X-ray doesn't show anything, your doctor might request a CT scan. This can give your doctor more information about the size, shape, and position of a known tumor, and check if your cancer has spread to the lymph nodes.
Several other tests can help your doctor definitively diagnose lung cancer, including sputum cytology, in which your doctor examines your mucus for cancer cells, and a lung biopsy.
If your doctor suspects a neuroendocrine tumor, they'll use blood and urine tests to look for hormone-like chemicals made by this type of tumor. They'll also perform pulmonary function tests to see how well your lungs work.
Rarely, your doctor may use PET scans and other radionuclide scans to help diagnose cancer.
The outlook for lung neuroendocrine tumors varies depending on your specific tumor type.
Typical carcinoid
This type of tumor has a very positive outlook. Both the 5-year and 10-year survival rates are over 90%.
Atypical carcinoid
Atypical carcinoid tumors have a 5-year survival rate of about 70%. The 10-year survival rate is around 50%.
Small-cell lung cancer
The 5-year survival rate for SCLC depends on how far it has spread. But SCLC has a generally poor outlook, with an overall 5-year survival rate of 7%.
The 5-year survival rates are:
Large cell neuroendocrine carcinoma
The 5-year survival rate of large cell neuroendocrine lung carcinoma also depends on your stage at diagnosis. However, because this cancer is hard to diagnose and stage, each stage has a wide range of survival rates:
People who receive a diagnosis of stage 4 large cell neuroendocrine carcinoma are unlikely to survive 5 years after diagnosis.
Keep in mind that survival rates reflect data from previous years. As treatments emerge and improve, survival rates tend to increase. Talk with your doctor about any new information that might improve your outlook.
Lung neuroendocrine tumors are a less common type of lung cancer. SCLC accounts for about three-quarters of all lung neuroendocrine tumors and has a poorer outlook. But some lung neuroendocrine tumors, like carcinoids, are extremely treatable and have higher survival rates.
Because the different types of lung neuroendocrine tumors have different outlooks and treatments, it's important to get a proper diagnosis.
Talk with your doctor if you have symptoms of lung cancer or hormonal problems, as these can be a sign of a neuroendocrine tumor.
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